1. Chapter 4 Notes Cell Physiology
Biology
Hamilton Science Department

2. Homeostasis
Organisms must maintain a balance of materials that enter and leave their cells.
Without this ability, they will die.

3. The Plasma Membrane
The property of a membrane to allow only certain particles through while keeping others out is known as selective permeability.

4. Permeability
Non-permeable- no materials can get into or out of the membrane
Semi-permeable- based upon size of the material, some molecules can get through while other can’t.
Permeable- Most or all molecules can move through the membrane

5. The FLUID MOSAIC MODEL of the Plasma Membrane

6. Polar Head
Non polar Tails

7. Plasma Membrane Structure
Marker Protein
Channel Protein
Receptor Protein
Lipid Bi-Layer

8. PASSIVE TRANSPORT- no energy required
DIFFUSION:
THE NET MOVEMENT OF PARTICLES FROM HIGHER CONCENTRATION TO AN AREA OF LOWER CONCENTRATION

9. Diffusion is a CONTINUOUS MOVEMENT UNTIL DYNAMIC EQUILIBRIUM IS REACHED.
Until EQUAL AMOUNTS OF SUBSTANCE ARE ON BOTH SIDES OF THE MEMBRANE

10. PASSIVE TRANSPORT continued..
2. OSMOSIS:
DIFFUSION OF WATER MOLECULES THROUGH A SELECTIVELY PERMEABLE MEMBRANE.

11. 3 TYPES OF SOLUTIONS AROUND A CELL:
1. ISOTONIC: CONCENTRATION OF DISSOLVED SUBSTANCES AND WATER SAME ON BOTH SIDES OF MEMBRANE
2. HYPOTONIC: CONCENTRATION OF DISSOLVED SUBSTANCES IS LOWER THAN IN THE CELL
CONTRACTILE VACUOLES: PROTISTS HAVE THESE ORGANIELLES - COLLECT EXCESS WATER AND EXCRETE IT SO CELL DOESN’T BURST
3. HYPERTONIC: SOLUTION. CONCENTRATION OF DISSOLVED SUBSTANCES IS HIGHER THAN IN THE
CELL.

12. Hypertonic Solution– Hypotonic Solution-
If a cell is placed in a…….
Hypertonic Solution– Hypotonic Solution-
Water moves out
of the cell
Water moves
into the cell!!
ISOTONIC SOLUTIONS ARE BALANCED !!

14. TURGOR PRESSURE –
The water pressure inside a plant cell.
HIGH TURGIDITY = CRISPNESS
LOW TURGIDITY = WILTEDNESS

15. PLASMOLYSIS:
LOSS OF WATER FROM A CELL RESULTING IN A DROP IN TURGOR PRESSURE
CYTOLYSIS:
GAINING OF WATER IN THE CELL CYTOPLASM,,,THUS AN INCREASE IN TURGOR!

16. FACILITATED DIFFUSION:
TRANSPORT PROTEINS
PROVIDE OPENINGS FOR PARTICLES TO PASS THROUGH – EX: SUGARS
FROM HIGH TO LOW CONCENTRATION.

17. The Plasma Membrane
The “ion channel” allows sodium, calcium, and potassium ions to enter and leave the cell.
called Ion Pumps

18. ACTIVE TRANSPORT
REQUIRES ENERGY
MOVEMENT OF SUBSTANCES FROM LOW CONCENTRATION. TO ALREADY HIGH CONCENTRATION
EXAMPLE:
MINERALS INTO CELL - SCARCE
Substances move
AGAINST GRADIENT

19. ENDOCYTOSIS:
USE ENERGY TO TAKE IN LARGE PARTICLES. CELL SURROUNDS THE PARTICLES - DOESN’T PASS THROUGH CELL MEMBRANE

20. PHAGOCYTOSIS: “CELL EATING” TAKE IN WHOLE PIECES BY PINCHING IN MEMBRANE

21. PINOCYTOSIS: “CELL DRINKING” TAKE IN FLUID BY PINCHING IN MEMBRANE

22. EXOCYTOSIS:
RELEASE OF WASTES FROM CELL VACUOLE. VACUOLE FUSES WITH MEMBRANE AND CONTENTS ARE RELEASED TO OUTSIDE.